1. Field of the Invention
The present invention relates to 1,2-dioxetane derivatives which can be used, for instance, as chemiluminescent substrates for immunoassays.
2. Discussion of Background
Varieties of 1,2-dioxetane compounds have been conventionally synthesized. In particular, 1,2-dioxetane compounds substituted with a spiroadamantyl group at the 3 position thereof disclosed in Japanese Patent Publications 5-21918 and 5-45590, and compounds disclosed in Japanese Laid-Open Patent Applications 8-169885 are known to be useful as chemiluminescent substrates.
The above-mentioned conventional compounds exhibit high luminescence efficiencies in non-protonic solvents. However, the luminescence efficiencies thereof are extremely lowered in water or in protonic solvents. The luminescence occurs when an anion in the excited state returns to the ground state. However, the anion in water or protonic solvents returns from the excited state down to the ground state, losing its activity nonradiationally, due to various effects caused, for example, by hydrogen bonds and dipole interaction of such solvents, so that the luminescent efficiency is significantly lowered in water or protonic solvents.
Therefore even when the luminescences of such conventional compounds are applied to immunoassays in clinical examinations, since the clinical examinations are conducted in protonic solvents, luminescence with sufficient intensity for use in practice cannot always be obtained. Therefore, it is necessary to use an enhancer in order to improve the luminescence at such clinical examinations.